The continuous flexible tubing made and formed by the machine and method of the present invention is of the type shown in Richitelli U.S. Pat. No. 3,199,541. The cross sectional configuation of the strip from which the tube is made includes a longitudinally extending bead along one edge portion and a longitudinally extending downwardly facing groove along the other edge portion of the strip, the groove being configured to correspond with the shape of the bead to snugly interlock therewith. Richitelli U.S. Pat. No. 3,199,541 describes forming of the tubing by wrapping the strip of flexible material helically about a mandrel with the flat bottom surface of the strip in contact with the mandrel.
In Fairchild U.S. Pat No. 3,778,327 a flexible tubing is formed on a mandrel means which comprises a pair of rollers having their axes in askew relation, the mandrels being formed with annular grooves. Fairchild discloses the wrapping of a strip of flexible material which is planar about the roller surfaces and at the same time feeding a wire onto a portion of the strip and in alignment with a groove in the mandrel so that the tension of the wire and strip cause the face of the strip in contact with the mandrel to conform to the mandrel groove formation. In Fairchild the strips of material are overlapped and the wire serves to reinforce the tubing. In Fairchild U.S. Pat. No. 3,778,327 both rollers of the mandrel means include annular grooves and only one of the rollers is driven, the other roller being an idle roller.
Both of the above U.S. Pat. Nos. 3,199,541 and 3,778,327 are owned by Automation Industries, Inc. which is also the owner of the present invention and application.